Device for the treatment of a medical fluid

ABSTRACT

A device for the treatment of a medical fluid including a permanently installed fluid treatment machine and a cassette with fluid-carrying channels as well as an elastic matt placed between these two items. The matt channels are recessed in the elastic matt and are provided with slits. Via the matt channels, an optimised vacuum distribution takes place and the slits serve the purpose of removing air between the cassette and the fluid treatment machine.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for the treatment of a medical fluidincluding a permanently installed fluid treatment machine, a cassettewith fluid carrying channels and an elastic matt placed between thefluid treatment machine and the fluid-carrying channels.

2. Description of the Related Art

Such devices are generally known and consist of a permanently installedfluid treatment machine, a cassette with fluid carrying channels whichare sealed with a foil, and an elastic matt placed between these twoitems. Medical fluids to be treated can be blood, for example, but alsodialysis fluids for the peritoneal as well as the haemodialysis. Therelevant cassettes are advantageously formed as disposable units. Such afluid treatment machine can also be a device for measuring of parametersof medical fluids, for example, as described in the DE 198 37 667 A1.

In these devices, a low pressure is created between the elastic matt andthe cassette in order to prevent a deformation of the foil during lowpressure in the channel, which leads to a channel restriction in thecassette, in order to be able to lift the foil at the adding points forthe medical fluid and thus keep the access free, in order to prevent anair compliance in the pumping device and in order to be able toguarantee at special sensor positions an air-free attachment between thesensor surface and the foil.

The extraction of air requires openings on the machine and an extractionunit connected to them, a vacuum pump for example, whereby thedistribution of the vacuum should be guaranteed to be as evenly aspossible and positive across the entire foil surface of the cassette.

SUMMARY OF THE INVENTION

It is the object of the present invention to further develop the genericdevice such that, during operation, a problem-free air extraction ismade possible whereby in this case the vacuum should be evenlydistributed across the surface of the elastic matt and a simple andproblem-free air extraction should be possible while, during themachine's idle time, the openings necessary for the air extractionshould at least be largely closed.

In terms of the invention, this object is solved by a device for thetreatment of a medical fluid including a permanently installed fluidtreatment machine, a cassette with fluid carrying channels and anelastic matt placed between the fluid treatment machine and thefluid-carrying channels. The matt channels are recessed in the elasticmatt, with the path of said channels following the fluid-carryingchannels of the cassette. Starting from a vacuum connection of theelastic matt to the extraction unit, the matt channels reach allimportant points of the elastic matt. In order to avoid leaks whenapplying pressure to the channel beads of the top-mounted cassette,these matt channels lie within the channel structure of the cassette.Only where, within the cassette, too, there is a channel or anotherfluid-carrying structure as part of the cassette, there is also acorresponding matt channel in the elastic matt. In the matt channels,slits have been placed. These slits provided in the elastic matt behavein a similar manner as a lip seal. As a result of applying a vacuum, aircan be extracted from between the fluid treatment machine and thecassette because the perimeter areas of the slits are pulled in due tothe vacuum and its connection to an opening. However, due to the returnforce of the elastic material, these slits close immediately once thevacuum connection is interrupted, i.e. when the device is in an idlestate or when there is no significant differential pressure. In thisstate, an ingress of fluid is securely prevented. On the other hand,when the slits are open, the access to the extraction unit, i.e. thecontinuation from the matt to the vacuum pump, can be protected againstunintended ingress of fluid by suitable measures (e.g. filter).

According to a preferred embodiment, along the matt channels, the slitscan be interrupted repeatedly for short intervals. That way, the slitsare afforded a sufficient stability which enhances their valve function.

At certain points, a continuation of the vacuum line is not possible viathe matt channels that run within the cassette channels because thereare, for example, recesses provided in the elastic matt, which interruptthe matt channels. These recesses engage, for example, with pumpmembranes or valves on the machine. This structure would lead to asituation where a trouble-free air extraction via the matt channels canno longer take place. In order to nevertheless provide a full surfacecontact between the cassette and the machine, with said contact being asleak-proof as possible, and in order to extend the required vacuumsource efficiently to the various areas of the contact surface,additional flatter connection channels compared to the matt channels areformed here, which by-pass the large-area recesses within the elasticmatt. The execution of these connection channels is so shallow and sonarrow that the nearby matt material of the elastic matt retainssufficient self-stability in order to prevent a deformation and closingof the connection channel even during the application of the vacuum andthe distortion. Due to this preferred design, it is guaranteed that theslits and channels during distortion and application of the vacuumremain open and the matt remains sufficiently stable while the sealingeffect of the matt remains intact and the channel structure provided issufficient for the air flow to be extracted.

Finally, in the preferred arrangement, the elastic matt is designed tobe exchangeable.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and advantages of the invention are explained moreclosely by way of an embodiment shown in the drawing. Shown are:

FIG. 1: a schematic, 3D representation of a section of an elastic mattaccording to an embodiment of the present invention,

FIG. 2: a section along the section line A-A′,

FIG. 3: a section along the section line B-B′, and

FIG. 4: a section along the section line C-C′.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

In FIG. 1, an elastic matt 10 is shown schematically which is arrangedbetween a fluid treatment machine, of which no detail is shown here, anda cassette (disposable) which is usually formed as a disposable unit. Onthe so-called machine side, namely on the surface which, when assembled,faces the fluid treatment machine, matt channels 12 and connectionchannels 14 are formed. Furthermore, a recess 16 is arranged in theelastic matt 10, into which in the assembled condition a machine-mountedvalve, for example, engages and establishes a seal all around. It iseasy to see that this machine-mounted valve interrupts the respectivematt channel 12 which happens to join the recess 16. In order to stillmake an air extraction possible, a connection channel 14 has beenprovided which connects the two interrupted branches of matt channel 12and connects them in turn with a further, parallel matt channel 12. Thestructure shown here is, of course, only an example and can be changedin any way. While the channel structures are provided on the machineside of the elastic matt 10, the disposable side, namely the side facingthe cassette, is executed as a smooth, i.e. flat surface.

By referring to the sectional views of FIGS. 2 to 4, the structure ofthe individual channels can be explained in more detail. The sectionA-A′ as per FIG. 1 is shown in FIG. 2 where a matt channel becomesvisible which, with the elastic matt used here having a thickness of 4mm, has a depth of 3 mm and a width of 2 mm. In the remaining mattmaterial below channel 12, which has a thickness of 1 mm, a slit 18 isplaced which takes on a type of valve function. When a vacuum isapplied, the two areas of the elastic matt 10 adjacent to the slit 18will open and enable the extraction of air gas. In an idle state or whenan equilibrium is obtained, the two adjacent areas return to theiroriginal position and close the opening. In order to enhance this returneffect, areas between the slits 18 are provided in the matt channel 12,which on the one hand do not have a slit and, on the other hand, areless deeply recessed in the area of matt channel 12. A correspondingarea can be seen in section B-B′ as per FIG. 3 which shows that, whilethe matt channel 12 in this area has the same width of 2 mm, it only hasa depth of 1 mm.

In the view as per FIG. 4, a connection channel 14 is shown in thesectional view of C-C′, where said channel is narrower and not as deepas the matt channel 12, which can be seen clearly in this view. In thiscase, both the width of the connection channel 14 and the depth are onemillimetre each.

With the elastic matt according to this invention, it is guaranteed thatthe interior space of the fluid treatment machine, in its idle state, isprotected by the self-closing feature of slits 18. At the same time, aneven air extraction is achieved between the fluid treatment machine andthe cassette across its entire surface because parallel extraction takesplace via numerous slits 18. Thus, a minor blockage may not cause anydetrimental effects for other areas.

With a thin matt 10, as it has been presented in the embodiment forexample, the opening effect of the slits can be utilised by applying avacuum.

Since the elastic matt 10 is exchangeable, it can be replaced easilyafter contamination or a fault. It is especially advantageous that nostructured shapes are required for the fixed components on the machine.On the side of the elastic matt 10 facing the machine, open structurescan be formed so that no sub-surface tunnels or other closed structuresare required. On the other hand, the side of the elastic matt 10 facingthe cassette is largely formed as a smooth, closed surface which can becleaned easily for example.

The invention being thus described, it will be apparent that the samemay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be recognized by one skilled in the art areintended to be included within the scope of the following claims.

1. A device for the treatment of a medical fluid, said device comprisinga permanently installed fluid treatment machine, a cassette with fluidcarrying channels and an elastic matt placed between the fluid treatmentmachine and the cassette, said elastic matt extending over substantiallyan entire face of said cassette and protecting an interior space of thefluid treatment machine, said matt having a substantially uniformthickness across said face into which channels are recessed, with pathsof said matt channels respectively corresponding with paths of thefluid-carrying channels of the cassette and with slits being provided inthe matt channels that extend from the matt channels to a side of saidmatt facing the cassette such that said slits overlie said cassettefluid-carrying channels, said fluid-carrying channels being distinctfrom any pump and valve regions in said cassette, said slits extendinglongitudinally along at least part of a length of the matt channels soas to run substantially parallel therewith, said slits being repeatedlyinterrupted for short intervals to form slitted areas and non-slittedareas, said slits being configured to act as lip seals.
 2. The deviceaccording to claim 1, wherein the matt channels in the slitted areas aremore deeply recessed than in the non-slitted areas.
 3. The deviceaccording to claim 1, wherein the elastic matt further includesconnection channels having a shallower depth than a depth of said mattchannels.
 4. The device according to claim 3, wherein said connectionchannels extend to provide a continuous path around interruptions in thematt channels which correspond with machine-mounted pump membranes andvalves.
 5. The device according to claim 1, wherein the elastic matt isexchangeable.
 6. The device according to claim 1, wherein the elasticmatt is sealable around a perimeter area of the cassette by puttingpressure onto a circumferential seal edge contained within the cassettearea.
 7. The device according to claim 1, wherein said cassette includesat least one of a valve region and a pump region, said matt furthercomprising a corresponding matt valve region or a corresponding mattpump region that overlies said valve and/or pump regions of saidcassette, respectively.
 8. The device according to claim 7, wherein saidmatt valve or pump region interrupts at least one of said matt channelsto form two interrupted branches, said matt further including aconnection channel that joins said two interrupted matt channelbranches.
 9. The matt according to claim 1, wherein said matt channelsare elongated and substantially linear with a width of approximately 2mm.
 10. The device according to claim 1, wherein edge areas of said matthave the same substantially uniform thickness as non-recessed centralareas of said matt.
 11. The device according to claim 1, wherein thecassette-facing side of said matt is a flat surface, said flat surfaceextending uninterrupted over portions of said cassette-facing sidepositioned over said slitted areas.
 12. A device for the treatment of amedical fluid, said device comprising a permanently installed fluidtreatment machine and an elastic matt for attaching a cassette withfluid-carrying channels, said matt having a substantially uniformthickness into which channels are recessed, with a path of said mattchannels being arranged to correspond with a path of fluid-carryingchannels of a cassette to be attached, and slits being provided in thematt channels that extend from within the matt channels to an oppositeside of said matt, said matt channels being distinct from any pump andvalve regions in said matt, said matt further having a substantiallyrectangular shape that, when attached to a cassette, extendssubstantially across an entire face of the cassette to effect an evenair exchange across said face and which can accommodate variousarrangements of fixed components on the fluid treatment machine.
 13. Thedevice according to claim 12, wherein the elastic matt further includesconnection channels having a shallower depth than a depth of said mattchannels.
 14. The device according to claim 12, wherein the slits extendlongitudinally along at least part of a length of the matt channels soas to run substantially parallel therewith, said slits being repeatedlyinterrupted for short intervals to form slitted areas and non-slittedareas, said slits being configured to act as lip seals.
 15. The deviceaccording to claim 14, wherein the matt channels in the slitted areasare more deeply recessed than in the non-slitted areas.
 16. The deviceaccording to claim 12, wherein said matt channels are elongated andsubstantially linear with a width of approximately 2 mm.
 17. The deviceaccording to claim 12, wherein edge areas of said matt have the samesubstantially uniform thickness as non-recessed central areas of saidmatt.
 18. The device according to claim 12, wherein the opposite side ofsaid matt is a flat surface, said flat surface extending uninterruptedover portions of said opposite side positioned over said slitted areas.19. An elastic matt for use in a device for the treatment of a medicalfluid, said device including a permanently installed fluid treatmentmachine and a cassette with fluid carrying channels and at least one ofa valve region and a pump region distinct from said fluid carryingchannels, said elastic matt comprising an exchangeable body memberhaving a substantially rectangular shape that can accommodate variousarrangements of fixed components on the fluid treatment machine andhaving a substantially uniform thickness into which a plurality of mattchannels are recessed with paths of said matt channels respectivelycorresponding with paths of the fluid-carrying channels of the cassetteand at least one of a matt valve region and a matt pump region distinctfrom said matt channels, said matt channels having a plurality of slitstherein that extend from the matt channels to a side of said matt thatfaces the cassette, said elastic matt being placed between the fluidtreatment machine and the cassette with said matt channels and slits inalignment with said cassette fluid-carrying channels and with said atleast one matt valve region and said matt pump region in alignment withsaid at least one valve region and said pump region of said cassette,respectively.
 20. The matt according to claim 19, wherein the elasticmatt further includes connection channels having a shallower depth thana depth of said matt channels.
 21. The matt according to claim 19,wherein the slits extend longitudinally along at least part of a lengthof the matt channels so as to run substantially parallel therewith, saidslits being repeatedly interrupted for short intervals to form slittedareas and non-slitted areas.
 22. The matt according to claim 21, whereinthe matt channels in the slitted areas are more deeply recessed than inthe non-slitted areas.
 23. The matt according to claim 19, wherein saidat least one valve region and pump region interrupts at least one mattchannel to form two interrupted branches, said matt further including aconnection channel that joins said two interrupted matt channelbranches.
 24. The matt according to claim 19, wherein edge areas of saidmatt body member have the same substantially uniform thickness asnon-recessed central areas thereof.
 25. A device for the treatment of amedical fluid, said device comprising a permanently installed fluidtreatment machine, a cassette with fluid carrying channels and anelastic matt placed between the fluid treatment machine and thecassette, said elastic matt extending over substantially an entire faceof said cassette and protecting an interior space of the fluid treatmentmachine, said matt having a substantially uniform thickness across saidface into which channels are recessed, with paths of said matt channelsrespectively corresponding with paths of the fluid-carrying channels ofthe cassette and with slits being provided in the matt channels thatextend from the matt channels to a side of said matt facing the cassettesuch that said slits overlie said cassette fluid-carrying channels, saidfluid-carrying channels being distinct from any pump and valve regionsin said cassette, said matt having a substantially rectangular shapethat can accommodate various arrangements of fixed components on thefluid treatment machine.
 26. The matt according to claim 19, wherein thecassette-facing side of said matt is a flat surface, said flat surfaceextending uninterrupted over portions of said cassette-facing sidepositioned over said slitted areas.
 27. A device for the treatment of amedical fluid, said device comprising a permanently installed fluidtreatment machine, a cassette with fluid carrying channels and anelastic matt placed between the fluid treatment machine and thecassette, said elastic matt extending over substantially an entire faceof said cassette and protecting an interior space of the fluid treatmentmachine, said matt having a substantially uniform thickness across saidface into which channels are recessed, with paths of said matt channelsrespectively corresponding with paths of the fluid-carrying channels ofthe cassette and with slits being provided in the matt channels thatextend from the matt channels to a side of said matt facing the cassettesuch that said slits overlie said cassette fluid-carrying channels, saidfluid-carrying channels being distinct from any pump and valve regionsin said cassette, said elastic matt further including connectionchannels having a shallower depth than a depth of said matt channels,said connection channels extending to provide a continuous path aroundinterruptions in the matt channels which correspond with machine-mountedpump membranes and valves.